This invention in general relates to optical viewing devices and in particular to a dual purpose optical device that is convertible between one mode of operation in which it serves as binoculars and another mode of operation in which it is a stereoscope.
Stereoscopic viewers, or stereoscopes, and binoculars are well known. One very popular type of stereoscope has long been provided under the name ViewMaster.RTM.. The View-Master.RTM. device has a housing that includes a roughly square, relatively thin, main body with a pair of elongated hollow tubes projecting from one end face. The main body is provided with an open slot along its top side to vertically receive a circular reel carrying stereo pair images. Each reel is a card that contains fourteen, color photographic transparencies arranged as seven opposing stereoscopic pairs. The subject of each pair is taken from two slightly different viewing perspectives so that, when the pairs are simultaneously viewed through the viewer, a stereoscopic (3-D) effect is provided. To view the stereo pairs, eyepieces are placed in apertures at the ends of the elongated hollow tubes. An advance lever is provided in the main portion of the body partially overlapping the reel and partially projecting from the body to form a handle. The reel can be advanced in the main body by movement and release of the handle. The end face of the main body opposite the end face supporting the eyepieces is normally provided with two translucent covers (or a single large translucent cover) which are in line with eye openings in the eyepieces and pairs of windows provided through the advance lever and through the opposing end face of the housing. The windows permit back lighting of the photographic transparencies for viewing through the eyepieces. Further details regarding the original View-Master.RTM. stereoscopic viewers can be found in U. S. Pat. No. 2,511,334, which is incorporated by reference herein in its entirety.
View-Master.RTM. stereoscopes have long been valued as both toys and educational devices. These viewers have been widely available and have been providing color images to both children and adults long before color television became common. They still provide three-dimensional images with a realism that cannot be achieved with any other consumer-available technology.
As valuable as such viewers are, it would be desirable to both improve the performance of such devices and to otherwise make such viewers more versatile to enhance their entertainment value, their educational value, or both.